Conventionally, in an electronic device having an imaging function such as a digital still camera or a digital video camera, for example, a solid state imaging element such as a charge-coupled device (CCD) or complementary metal oxide semiconductor (CMOS) image sensor is used. The solid state imaging element includes a pixel in which a photodiode (PD) that performs photoelectric conversion and a plurality of transistors are combined, and an image is constructed on the basis of pixel signals outputted from a plurality of pixels arranged in a planar way. The pixel signals outputted from the pixels are, for example, A/D-converted by a plurality of analog-to-digital (A/D) converters arranged individually for columns of pixels, and are outputted.
For example, in Patent Literature 1, a solid state imaging element including an A/D converter configured to include a comparator that compares a saw wave-like ramp signal and a pixel signal and a counter is disclosed. Further, in Patent Literature 2, a solid state imaging element in which, in an A/D conversion system called a single-slope integration type, gain adjustment can be made by changing the slope of a reference signal supplied to a comparison circuit is disclosed.